Contact for vibrators, relays, or the like



Aug. 26, 1941. s. .WOLTER 2,253,672

CONTACT FOR VIBRATORS, RELAYS; OR THE LIKE Filed March 23, 1939 INVENT OR.

GEQHA RD WOLTER ATTORNEY.

Patented Aug. 26, 1941 2,253,672 CONTACT FOR VIBRATORS, RELAYS, on THE LIKE- G'erhard Welter, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic 111. b. 11., Berlin, Germany, a corporation of Germany Application March 23, 1939, Serial No. 263,744 In Germany March 23, 1938 1 Claim.

The lifetime of pressure contacts, which are opened and closed very frequently, as at a vibrator (a mechanical interrupter or rectifier) or at a relay, and which controls substantial electrical power, is often reduced by the so-called pinformation." This is a special form of the travel of material, whereby a pin-like excrescence arises almost at the cathode and a relatively deep crater in the anode at the corresponding place. This pin-formation causes a fast destruction of one contact piece (mostly of the anodic contact), as it will soonbe perforated. I

The main object of the present invention is to avoid this disadvantage. For this reason the two contact pieces are constructed of different conductors or semi-conductors, which have different crystal-grid structures (for example cubic and hexagonal crystal-grid) or different inter-planer distances of the crystal-grid (for example 3 and 6.10" cm.), so that a tight growth of the one conductor or semi-conductor upon the other is avoided.

The invention makes it possible to obtain a considerable increase in the lifetime ofthe contact. This becomes evident as follows: The pin-formation begins by a little accumulation of material arising at a place in the anodic contact piece. At this place (that is at the originating pin-top) the field is the strongest. At the moment the contact opens and a spark or are arises, electrons bound against the anodic contact piece and release ions from the material of the anode. These loose ions are drawn preferably to the place of the strongest field, that is to the open place of the beginning pin-top. Further at the opening the liquid material which is formed by the spark or the arc is always travelling to the pin-top in consequence of capillary forces.

It is not always possible by the present invention to entirely avoid the travel of material. But if the materials of the two contact pieces are very diflerent in reference to the crystal grid structure (that is if these materials have substantially different crystal grid forms or have similar crystal grid forms, yet substantially different grid distances) a solid building up of the one contact material onto the surface of the other contact.

piece is impossible. At most a superficial atcontrolled.

tachmentarises, which is destroyed quickly by contact-touching. Therefore the pin-formation isb avoided and the lifetime increased considera 1y.

It is old to employ difierent metals for the two pieces of a contact. However, it-is not known to choose the metals or semi-conductors at the contacts of a vibrator or relay according the present invention.

In the accompanying drawing there is shown an embodiment of the invention in the form of a vibrator or mechanical interrupter. The vibrating reed F carries at each side two contact pieces K1 and K: which engage alternatively the two counterpieces K'1 and K2, carried by the springs G1 and G2. The vibrator may control a current of 1 or more amperes at a voltage of about 220 volts, so that power of about 200 watts can be The contact pieces K1 and K2 consist of .metals which have a cubic crystal grid form such as copper, silver, gold or the like. The counter pieces K'1 and K'z consist of materials which belong to the hexagonal crystal grid system such as zinc,'cadmium, ruthenium, osmium, cobalt, magnesium, beryllium or the. like. It is possible, of course, to employ instead of metals chemical compounds of metals which have no atom grid, but an ion grid and .also belong to the hexagonal system (binary crystals). These compounds are especially the semi-conducting carbides of hard metals such as silicon-carbide, Wolfram-carbide, tantal-carbide or so like.

In this way it is possible to raise the lifetime of the contact of a vibrator for a power of approximate 1 kilowatt to 10"10 openings.

What I claim is:

In a vibrator device, an electrical make-andbreak switch having a pair ofcooperating contacts, one of said contacts being composed of at least one of the metals having a cubic crystalline structure from the group including copper, silver and gold, the other contact being composed of at least one of the metals having a hexagonal crystalline structure from the group including zinc. cadmium, ruthenium, osmium, cobalt, magnesium and beryllium.

J GERHARD WOLTER. 

